NTSB Safety Recommendation Letter P-83-030

Page 1Official PDFNATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. ISSUED: November 4 , 1983 -------------------_____________________----” Forwarded to: Mr. Charles Royer President SAFETY RECOMMENDAT I ON ( S ) National League of Cities - - 1301 Pennsylvania Avenue, N.W. I Washington, D.C. 20004 Mr. Matthew Coffey National Executive Director National Association of Counties 440 First Street, N.W. Washington, D.C. 20001 -I_---__----------------------------- At 10 a.m., c.s.t., on February 1, 1983, a natural gas explosion and flash fire destroyed a house, killed two persons, and injured three persons at 705 S.W. First Street, in Pryor, Oklahoma, and damaged an adjacent house. Natural gas, escaping from a corroded 1/2-inch residential service line located beneath the house, filled the enclosed crawl space, and migrated through the floor and into the house where it was ignited by one of several appliance pilot lights. The city of Pryor, which owns the gas system, distributes natural gas to its customers by providing service lines to gas meters located at the residential property line. The gas pressure is reduced at the property line regulator from 15 to about 1/4 psig, about ‘7-inches of water column, for use in various indoor gas appliances. The gas company owns the service lines up to and including the meters. Beyond the meters, the service lines are the property and the responsibility of the building owners. During the investigation, pressure tests were performed from the gas main to about 3 feet inside the crawl space under the house; no leakage was detected. An inspection of the noncompany- owned piping revealed that the 1-inch residential service line entered the crawl space underground and emerged near the center of the crawl space as a 1/2-inch steel pipe. Corrosion was found 3681-A#

Page 2- 2 - on the pipe at the point where it emerged from the ground amination of the corroded segment revealed a hole located elbow, which was about 5 inches below ground surface. Furthe inspection of the area indicated that the aboveground crawl spac piping and the connecting piping to the indoor appliances were mixture of galvanized and steel piping. Company records indica ted that the portion of the service line upstream of the ga meter was installed in 1972. The records did not indicate the installation date of the downstream residential service line an the appliance piping. The provisions of 49 CFR 192, Subpart I -- Requirement f Corrosion Control, do not extend to noncompany-owned piping a the gas company acknowledges no responsibility for tt dential service lines or the indoor house piping. Consequently periodic gas leakage surveys or other tests to determine th condition of customer piping similar to those required by Section 192.723, Distribution systems: leakage surveys and p cedures, for company-owned piping are not performed. The Safety Board is concerned about the potential for sirni- lar accidents. Numerous buildings nationwide are served with natural gas through buried customer-owned, noncathodically pro- tected service lines, none of which are required by Federal regulations to have periodic gas leakage surveys or other tests to determine their condition and few of which are surveyed or tested. Therefore, the National Transportatio Safety Board recommends that the National Leagu'e of Cities an the National Association of Counties: Notiiy its member governments of the circumstances of this accident and urge them with respect to customer owned service lines not subject to Federal inspection requirements to institute requirements for periodic inspections of buried service 1 fcr corrosion. (Class 11, Priority Acti (P-83-30) The National Transportation Safety Board i s an ind Federal agency with the statutory responsibility ". . .to transportation safety by conducting independent accident gations and by formulating safety improvement recommen (P.L. 93-633). The Safety Board is vitally interested in an actions taken as a result of its safety recommendations a appreciate a response from you regarding action taken or templated with respect to the recommendation in this letter BURNETT, Chairman, GOLDMAN, Vice Chairman, and McADAM BURSLEY, and ENGEN, Members, concurred in ais recommendation.#